Wheel Bearing Adjustment.

johns4104s · April 21, 2009, 05:18:45 AM

I now Have everthing back in place. I dint see how I can torque the disc down that goes next to the bearing? What I did is screw the disc down until the wheel started to bind, then back the disc of 1/2 a turn, put the disc keeper on, then the nut keeper and finally the nut.
The wheel is still in a some bind, not completely free.
How do I torque the disc? Should the wheel be completely free, no bind whatsoever?

Thanks

John

JackConrad · April 21, 2009, 05:26:35 AM

Quote from: johns4104s on April 21, 2009, 05:18:45 AM
keeper and finally the nut.
The wheel is still in a some bind, not completely free.
How do I torque the disc? Should the wheel be completely free, no bind whatsoever?
Thanks
John

Are you sure the brake is not dragging, causing the bind? I forgot, did you pack the bearings with grease or are you using oil ? Jack

rv_safetyman · April 21, 2009, 05:45:03 AM

John, if you backed the wheel adjustment nut off 1/2 turn, you went way too much!

There is a good thread at: http://www.busconversions.com/bbs/index.php?topic=11060.msg115411#msg115411

I recently wrote an article for Bus Conversion magazine with a couple of additional sources about how to adjust wheel bearings, but the bottom line is the you should only back off the nut (after applying proper torque) less than 1/4 turn.

I had my wheels adjusted looser, and it caused pretty significant abnormal wear on the steering tires.

Jim

JohnEd · April 21, 2009, 10:37:35 AM

Engineers....ya gotta luv'em. Recently I was faced with your dilemma..HOW tight and HOW much to back off AND what exactly is a LITTLE bind? Tight was...."you know, really reef on it." Back off "a quarter turn OR SO and make sure there is no more bind". A little bind is where "there is SOME drag when you spin the tire". I have done this a hundred times on cars without even a hiccup....tight with a half inch breaker bar that I leaned on.....back off till I could just "bump" into the bearing when tightening....lock it down. Well, this ain't my 240Z and this lash up(bus) has "no feel" like a car.

Here is the real deal...hot skinny and inside track: It turns out that you can do this any way your heart desires, including chanting, as long as you end up with 1 to 5 thousandths of movement :AFTER" you are done. That is the grease and expansion clearance, I assume, but it is the final word as I read it. Well Partner, I went out and bought the dial indicator with the special rack and clamp and flex coupling and assembled same. Set it aside till I got the bearing tight, then backed off, then bumped into tight, then backed of 1/16Th of a turn. Final act is LOCK DOWN THE JAM NUT to 180 lbs(WTF? Well,OK) I set up the dial ind and yanked out on the wheel and then pushed in on the wheel. TOTAL movement....3 thousandths. Cost me a lot of money and time but I KNOW the bearings are RIGHT. I have never seen a mech. do this but I haven't ever watched a truck or bus guy go thru the motions.

something to consider: You walk around you bus when you pull in and shoot the tires and hubs with the no contact laser gun, right? When a hub reads 20 or thirty degrees hotter than the rest, after many tests in different locations, what action do you take? Tear down the hub and repack or readjust bearing pre-load? How about measure the end play for 1 to 5 thousandths?

HTH

John

johns4104s · April 21, 2009, 05:46:50 PM

Were is the best place and most resonable place to buy a dial indicator and how do you use one?

Thanks

John

HB of CJ · April 21, 2009, 06:05:36 PM

First off, great post and thank you. Let's polish it. Tire and hub temps are Ok, but they are kinda subjective depending upon the time of year, hiway temps and length of service. Other factors determine over-heat of bearing areas.

An example: The pretty City of Bakersfield California in August. Your Fire Engine (very $expensive$) has just completed a high speed run up from L.A. due to some wildfire move up. They want you back in town soonest. Bearing temps?

Makes a big difference. Almost an art form. Subjective. Did I cover everything? Everything is going to be very very hot. Yes, an extreme situation or enviroment, but instrumental to determining what is hot and what is not.

Soss: how do we determine if bearings are too hot or not. Most of the time we can't. Best to set the bearing up based upon lots of experience and just hope for the best when all bets are off. We need baseline settings.

However, and I love qualifiers, most of the time it would be a great idea if one doesn't know exactly what one is doing, it may be best to let the "old man" set your bearing torques. Seems to save money in the long run. HB of CJ

bearing temp Post

buswarrior · April 21, 2009, 06:27:25 PM

If you get the bearings hotter than you can touch, best be very afraid.

Not heat soaked by the brakes, that's a different disaster.

So, how about this: hotter than ambient by more than 40-50 degrees, you want to think hard about what's what.

Bring it in for a landing real gently coming in off the highway, then the brakes won't be an issue.

Get an infra red heat gun and use it on everything, so you start getting a feel for what "normal" might be.

Haven't seen any temps, other than brake drum related, above 120 degrees on tires or bearings.

Sunny side of the street will be a little warmer.

Jump in with some general feelings, temp gun aficionados!

happy coaching!
buswarrior

gumpy · April 21, 2009, 07:55:26 PM

Quote from: buswarrior on April 21, 2009, 06:27:25 PM
If you get the bearings hotter than you can touch, best be very afraid.

Not heat soaked by the brakes, that's a different disaster.

So, how about this: hotter than ambient by more than 40-50 degrees, you want to think hard about what's what.

Bring it in for a landing real gently coming in off the highway, then the brakes won't be an issue.

Get an infra red heat gun and use it on everything, so you start getting a feel for what "normal" might be.

Haven't seen any temps, other than brake drum related, above 120 degrees on tires or bearings.

Sunny side of the street will be a little warmer.

Jump in with some general feelings, temp gun aficionados!

happy coaching!
buswarrior

Yes, this is pretty good.

I think my tire temps are usually around 90-95* F. I see brakes at around 120-130* F for normal light usage. I haven't been taking many hub temps lately, but
will start again on the next trip.

craig

JohnEd · April 21, 2009, 08:44:59 PM

All of you guys are great. I didn't have that absolute temp data so thank you there. The way I did this was that I measured "all" the hubs. I compared the temps between the hubs and considered fronts might be a little cooler than rears. "Sunny side" has no effect if you are just pulling over.

I used to just walk around and touch the hubs and I could tell by feel if any one was hotter. This is how I detected the bearing going bad in South Dakota and limped into Sioux Falls at 30 mph after 20 miles or so. Shop owner said I was the only one he had ever seen that came in with a bad bearing that wasn't on a hook. Lucky save. I detected this and was alerted by noting that my vacuum was down a pound and I was on the level and holding 50 with the cruise control. I had had a problem prior with brakes dragging and the symptom was depressed vac numbers.

I bought my dial indicator from Harbor Freight. Wasn't expensive. You want the one that comes with a vice grip as part of the clamping system and it also has a lever that causes the flex arm to go ridged. You clamp the vice grip to the frame behind the brake drum so pulling on the tire doesn't move the bus or assembly with respect to the hub. Lift the tire a little with a bar to take some of the weight off and push the wheel "IN". Then pull the wheel "OUT". The dial will indicate total travel of the hub and that is the clearance that is supposed to be 1 to 5 thousandths. You don't have to take the tire off but the thing weighs a couple hundred pounds or so and if you don't take some of the weight off the thing will just sit against the bottom of the races. No matter what the klutz or inexperience. 1 to 5 is "home". I went through all this to satisfy myself that the procedure that they specify is correct and you end up with perfect clearance recommended by Timkin. I will certainly repeat this if I start to get a warm hub or after X thousand miles as a PM check. I have time....I am retired and part of this is hobby/entertainment. No having much income other that a disability pension helps put "fun" into perspective.

YMMV,

John

JackConrad · April 22, 2009, 03:59:33 AM

When shooting bearing temps, or any temps for that matter, COMPARE! Both front hubs should be close to the same temp, maybe sunny side slightly hotter. Both tags should be close, both drive axle should be close. If shooting battery cable connections to find a poor connection, the poor connection should be hotter. Same with brake hubs, both front hubs should be close.
Compare apples to apples. Do not compare front hubs to tag hubs, etc. Also establish a baseline. I know our right cylinder head always runs about 5 degrees hotter than the left. Same with our front bearings, for some reason the right is always about 5 degrees hotter ( all bearings were cleaned, inspected, repacked,and re-installed). Jack

zubzub · April 22, 2009, 09:51:24 AM

I love my temp gun, when I first drove my bus I had no idea what kind of shape the hubs etc were in. Comparing temps first after 10 mins highway then 30 then 60 then every stop gave me a good feel for what was what. In the future any decent run will always end with me doing a quick walk around checking tires, drums, hubs, and the pumpkin.

bobofthenorth · April 23, 2009, 04:40:13 PM

My drives are generally 10 degrees hotter than the steers & tags. Its not unusual for the inside dual to be 5 or 10 degrees hotter than the outside. Sunny side always runs at least 10 degrees hotter on a hot day. I expect my towed to be similar to my steers & tags and then go up in temps from there. Hubs are usually somewhere in between the steer & drive temps. And I've seen over 130 on a hot day in the winter so I would expect those temps to get well up there on a southern summer day.